The invention regards a blade arrangement of a jet engine or an aircraft propeller. Embodiments of such blade arrangement include a fan blade arrangement and a propeller blade arrangement.
Jet engines and aircraft propellers need to be able to deal with the situation of a blade off event. A blade off represents a situation in which a structural failure of load bearing material of a blade occurs such that the blade brakes off and fragments of the blade separate, which can cause serious damage to the jet engine and the aircraft.
In the case of a fan blade, in order to be able to withstand the impact loads of a fan blade off, it is known to construct the fan containment case in a strong and stiff manner and to provide deflections at the front and rear flanges of the fan case. However, such construction significantly drives complexity, weight and costs of a fan case. Further, post fan blade off, there is a significant out of balance of the fan rotor, which requires multiple “fuses” to be designed into the power transmission system to allow the fan rotor to spin concentric to its new center of mass. Such design further adds complexity, costs and weight to the system. Still further, in order to deal with out of balance loads after a fan blade off event, also the rest of the engine structure needs to be strengthened and stiffened and such strengthening and stiffening requirements may extend into the nacelle, pylon and the aircraft itself. Again, complexity, weight and costs of the engine structure are increased.
Similar or related problems occur if a compressor blade, a turbine blade or a propeller blade break.